The present invention relates in general to power and cooling architectures, and more particular, to flexible power and cooling architectures integrated in a common machine.
In modern military aircraft design, system integration offers a balanced design in weight, performance, cost and volume that potentially yields an optimum system solution. In terms of air vehicle subsystem in recent years, a lot of emphasis has been placed on the integration of power and cooling systems. For example, in U.S. Pat. No. 4,684,081, a typical auxiliary power unit (APU) is mechanically coupled to an engine shaft and a heat exchanger is integrated to the downstream of a compressor to form a primary auxiliary power system. The engine power is used to compress ambient air for air conditioning as well as power production in flight. As understood, the mechanical linkage ultimately complicates the engine configuration. In U.S. Pat. No. 4,494,372, a compressor and a free turbine is added to the multi-role primary/auxiliary power system as disclosed in U.S. Pat. No. 4,684,081. The additional features did not reduce the complexity of the engine configuration.
U.S. Pat. No. 4,503,666 adds a cooling turbine and a complex clutch mechanism to an auxiliary power unit that provides engine starting function (pneumatically), supplemental power and environmental control function. U.S. Pat. No. 5,442,905 uses a turbo machine composed of a first open loop expansion turbine, a generator, a closed loop compressor and a second turbine to form a cooling and power system. It requires an uncoupled auxiliary power unit to perform engine starting, ground and emergency power generation, and higher-stage bleed air expansion is required to provide the engine to drive the closed loop circuit. In U.S. Pat. No. 5,490,645, a unit consisting of two turbo machine modules and associated heat exchangers and valves is proposed to provide power for engine starting, ground and emergency operation and environmental control. The unit operates as an independent system and requires full-time combustion in flight to compress the ambient air for cabin pressurization.
U.S. Pat. No. 6,415,595 discloses a turbo machine consisting two turbines and a compressor. U.S. Pat. No. 6,845,630 integrates a cooling and power turbine with a generator and a fan on the same shaft and uses preconditioned engine bleed air to produce power and cooling. Neither of the structure disclosed by U.S. Pat. No. 6,415,595 or 6,845,630 integrates the engine starting function, emergency power generation function, and cooling function. In both disclosures, an auxiliary power unit is required to perform these functions.
Although various approaches have been disclosed to address the power and cooling function, most of these approaches require a complex structure with unique machinery. It is therefore a substantial need to provide an architecture using a common machinery configuration and technologies which does not only improve the power and cooling efficiency, but is also easily reconfigured to be suitably adapted in various types of aircraft platforms.